Hey yall, new here. i was a mod on another gm gas truck site when i had my old truck so hopefully ill stay active on here also. So recently got me a 96 7.3 on 35s w 410 gears had 290 on it im at 297 now. i put a ts 6 position chip on it, aftermarket trans cooler, and air intake, deleted muffler. w after market down pipe. i have done my best to keep my foot out of it and the millage sits around 12. i mostly drive mixed, some hwy and mostly in town, with the occasional deer lease trip. i have been looking at doing injectors and or inter cooling it. any wisdom on what to get and how much better mpg im looking at?
thanks in advance!

In all reality doing performance mods to a truck really isn't going to get you much better mileage. Perhaps you might pick up 1 or 2 mpg more. But one question is has your speedometer/odometer been re calibrated for the larger tires? If not you could pick up a little right there by just getting the correct mileage.

I believe he is talking about programing the power train module with the proper tire size. An intercooler will not improve mileage, it will only lower exhaust gas temps. IMHO the only way to improve mpg is to drive like an egg is under the accelerator pedal and keep the hwy RPM's bellow 2000, I think the consensus is 1850 for best mileage.

Here's the procedure from Steve Baz's page:

Speedometer

Recalibrate Your Speedometer After Changing Tire Size

There is no tire size/code chart because tire size vs. actual tire dimensions are different between manufacturers. Even between the same tire size and same maker there will be a difference in actual size between the different tread designs.

Example:
Start with 20186, divide by actual tire size in inches. Divide again by .6666

You want to use a rolling measurement to get your actual tire height (If you try to measure the tire in the driveway, use conversion charts, or anything else you will end up with an inaccurate reading again). Use your rear tire since the sensor is located there. Mark the ground and your tire and roll forward 3 times marking the ground each time. (I ran over a spot of oil at a local gas station and measured between my tread mark prints), then divide that number by three to get the average length of one revolution (this will protect yourself against a bad reading using just one revolution). You can then divide the length of one revolution by 3.14 to get actual tire height. Be careful in your measurements, a small amount will change the code. EX: 31.69" tire height is code 956, and 31.21" tire height is code 970.

Now, to program it into your truck:

Warning: You can only change the calibration 6 times without replacing the module.

To set the calibration, ground the single wire connector under the glove box it says PSOM (Programable Speedometer Opdometer Module). ”Yes there is only one and it has a spade type plug on the end". I used a wire with clips on both ends to ground the plug to a screw under the dash or try a test light and use the clip end to the PSOM and the other jam in a dooe hinge. Now look at your speedometer on the face of your dash while sitting in the drivers seat and there should be a "reset" button and a "select" button. While holding the reset button in on the trip meter, turn the ignition to 'on' while the wire is still grounded. Let go of the reset button. The speedometer display will sweep once and will show a code of some kind then push in again the "reset" button and the existing code will be displayed with RECAL?, mine said 976 RECAL? Now you enter your new code you came up with by dividing the rolling measurement by PI or 3.14 by pushing the "select" button until it gets to the new calibration code number. You may have to push “select” a whole bunch of times until you get to your code. If you turn off the key at this point the original code will not be changed or any of the 6 lives will not be used. To store your new code press “Reset”. Turn off the key. Unplug the ground wire. To check the new calibration, use the mile markers on the interstate. Run an indicated 60 mph and it should take exactly 60 seconds to go 1 mile.

For injectors stick with a know company in the diesel truck world such as Swamps, Beans, or Rosewood. Once you have the injectors you will need to have your chip re-burnt for them. Then for the cooler you can pick up any of them for the Ford trucks 99+ years and then build your pipes yourself if you want to go that way or if you want to buy a whole kit I believe the Hypermax still builds a kit for the OBS trucks along with Banks.

For injectors stick with a know company in the diesel truck world such as Swamps, Beans, or Rosewood. Once you have the injectors you will need to have your chip re-burnt for them. Then for the cooler you can pick up any of them for the Ford trucks 99+ years and then build your pipes yourself if you want to go that way or if you want to buy a whole kit I believe the Hypermax still builds a kit for the OBS trucks along with Banks.

yes i was looking at swamps, w a banks cooler, what millage are you 2 getting in yalls 7.3s?
thanks

I'd say that 23 mpg is almost certainly not accurate. Either he believes his digital readout (which obviously isn't correct, especially if he has a programmer on it) or he's not doing something correct with his hand calcs (not filling up the tank to the same level, his odometer is off, etc.).

I would be willing to bet that the best mileage that you are going to get with a OBS truck is going to be around 22mpg. That is going to be with stock tires and a 3:55 rear end. Or if you are running 4:10's you are going to have to keep the RPM's on a road trip under 2000 rpm. I know since I have done it, but that was one slow trip.

I suspect that most of your low MPG comes from the big tires, even if your speedo was recalibrated those big tires raise the truck up high enough to increase aero drag. Where and how you drive makes a HUGE difference.

I ran a set of 255-85R16's on my '96 for several years & 127,000 miles, and in summer cruising the Interstate to/from work @ 68-72 MPH I averaged 20 MPG or just a bit better for three months & 10,000 miles. Running the A/C on hot days resulted in better MPG that running with the windows open, but maybe that was more to do with the slightly hotter engine temp too.

At 60 to 65 mph I can get 21 to 22 mpg easily. only thing done to mine is AFE breather, down pipe and 4" exhaust w/cat delete, Edge Evolution set on extreme,and replaced the clutch. Got to keep your foot out of it for the mileage to pick up.

'96 F-250, ext. cab, 2 wheel drive, long bed, AFE stage I intake, Baby Swamps, down pipe and 4" exhaust with cat delete, Edge Evolution (soon to be TS 6 position chip). works hard every day on the job hauling pipe and tools and then on the farm at night and weekends. the best never rest!

On a hot day, not much wind, on the (flat) New York state thruway, on about 150 mile round trip, at 67 mph, refilled at same gas station, I got around 22-23 mpg. stock truck with road tires. Around town in the summer i get about 17-18, but i do a lot of coasting up to street lights and roll thru them green most of the time. 3:55's

wait?!? increasing my tire size to 35's will decrease my mpg? I've been told and read that the larger tire size will bring my RPMs down and give me better milage. Seems here, people are saying that the bigger tires and increased lift will reduce MPG..

I plan to put a 3 inch RSK on mine and 35s. Should I expect to see worse mpg? I drive mainly on the freeways at about 65 to 70 mph with 4.10s

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